The invention relates to a wind tunnel compressor rotor assembly method. The method includes: horizontally fixing an air outlet side shaft to an operating platform; assembling a hydraulic cylinder andthe air outlet side shaft; assembling a hub component and an air inlet side shaft; mounting each level of adjusting barrels into the hub component; assembling the hub component and the air inlet sideshaft. The wind tunnel compressor rotor assembly method has advantages that by adoption of a vertical assembly scheme, the problem of high-precision positioning of seam allowances of large-size partsis solved, assembly steps are simplified while assembly difficulty is lowered greatly, and accordance of various indexes with design requirements can be guaranteed after completion of wind tunnel compressor rotor assembly.